Most types of painting use an evaporative solvent to apply a coating to a substance. In 1945, a man named Daniel Gustin invented a different method that came to be known as powder coating. Powder coating machines don’t use wet application methods. Instead, a dry powder gets applied, adheres through electrostatic charge, and then cures through either the application of heat or UV radiation.
We discuss the popular types of powder coating machines, various applications for large- and small-scale powder coating equipment, and what you should consider when buying powder-coating machines.
The Powder Coating Process
Before we list the most commonly used powder coating equipment options, let’s discuss how powder coating works and its unique properties.
As mentioned above, powder coating is a dry powder rather than a liquid that dries to a solid film through evaporation. After using static electricity to cause the powder to adhere to the “painted” surface, powder coating must be cured in some way to make the powder harden and cling to the underlying material. The fact that both large and small powder coating machines don’t use liquid solvents has a number of practical considerations. First, many consider powder coating a more environmentally friendly approach than traditional painting. Second, because gravity doesn’t pull on electrostatically charged powder the same way it drags on liquid paint, powder coatings can be effectively applied in hard-to-reach areas. Finally, powder coatings can be applied more thickly than traditional paint, which grants them certain protective properties.
The method by which powder coatings are applied involves multiple steps. The first involves the preparation of the item to be coated. Because powder coating requires static cling for the process to work, the surface of the item must be entirely clean of impurities such as rust, scale, grease, dirt, and the like. Sometimes pre-treating involves scrubbing or blasting the item with an abrasive substance. Other options include spraying the item with or immersing it in chemicals such as phosphates. Certain composites may require a low-temperature air-plasma treatment in order to help the powder adhere to their otherwise slick surfaces.
The next step is the selection of the powder. The powder in powder coating is usually one of two formulations. Thermoplastic powder will adhere to surfaces when heated, which allows for the reuse of applied material, the recycling of overspray, and generally thicker coatings. Thermoset powder requires a curing process that either involves heat or UV and permanently bonds the substance. It typically finds application in contexts requiring high heat because it won’t melt once cured.
In order to apply the powder, it must be loaded and fired through a powder-coating gun. These guns impart an electrostatic charge to the powder, which causes it to adhere. Manual guns are simpler devices that allow users to dial in specific flow and voltage requirements prior to applying the powder by hand. Automatic guns do not require manual input and can even be part of fully automated units. Guns can come with many different nozzle types, and there’s one particular type of gun — the tribo gun — which uses a Teflon tube to charge the powder. A powder bell uses rotation to disburse a more homogeneous application of powder. Other means of application include a fluidized bed into which parts are dipped and an electrostatic magnetic brush which can facilitate hands-on applications at many different layers of thickness.
Popular Types of Powder Coating Machines: Ovens vs Booths
When examining powder-coating equipment, it’s less helpful to look at powder-coating booths and ovens as different, incompatible options. Rather, they serve complimentary purposes. A powder-coating booth simply functions as a space where one can safely apply the electrostatically charged powder to your item or items, as well as a way to reclaim unused material if feasible. The oven is the place where thermal, infrared, or ultraviolet radiation is applied in order to harden the powder coating.
When the powder is applied via a gun, it gets fed through a powder coating system. Think of these as the systems that bring the powder to the gun. Box feed units feature powder boxes that allow for easy swapping in and out of different powder batches (often used in applications that require many different colors). Hopper feed units are designed for single-batch, higher-volume applications.
Since powder coating involves the spraying of fine particulate matter, professional operations benefit from the use of a booth where the coating takes place. While booths serve a basic purpose of catching over sprayed powder, they can contain a number of different features. For instance, most booths have exhaust systems, and some even feature a reclaim system to recycle unapplied powder. Different booths will have different kinds of lighting and may even feature modular construction so that the booth can be expanded. A control panel will offer different amounts of oversight over a booth’s particular functions.
Ovens are where the final curing process takes place, and they can be categorized according to several different variables. The most important of these is whether the oven is based around conventional heat or infrared technology or ultraviolet technology. (Units can be further broken down by whether they use electricity or gas power.) The next major factor is size, and a powder coating machine and oven system can come in sizes from small hobbyist units to factory-level equipment. Finally, ovens typically come with either simple analog controls or advanced digital controls.
What to look for when buying Powder Coating Machines
No matter if you’re searching for a single powder coating machine for sale or looking for an entire powder coating equipment package, you ought to keep in mind a number of important topics prior to making a purchase. These include the following:
New vs Used
No matter the type of equipment, each specific piece will perform differently over time. Some powder coating machine manufacturers produce products that will stand up to the rigors of time, and some don’t. Some owners of those machines may treat them well, and some may run them ragged. Examine both the reputation of the producer and of the company making the sale to you. No one wants to overspend on new equipment, but buying a less-than-functional machine can also cause problems.
While not every one of the powder coating line machines, ovens, booths, and sundry additional pieces of equipment will still have a factory warranty, some will. Investigate to see if the equipment you want remains covered and how you would use that coverage in case of damage or loss.
Long-running manufacturers may continue to support their products even long after they’ve stopped manufacturing specific models. However, many will not, and in those instances, buying a used machine may become a major hassle if it breaks down.
Incorrect Power and/or Power Supply
Powder-coating machines are used the word over, and that means various machines may not be equipped to run on domestic power. Ensure that you won’t have to rewire a particular used offering prior to purchasing.
Different pieces of powder-coating equipment have various fail-safes and safeguards built in to ensure liability-free operation. As part of your due diligence, obtain guarantees that essential safety equipment is in full and working order.
If a curing oven is missing, say, a gas burner or a spray booth lacks its control panel, you may end up with a used piece of equipment worth far less than the price you paid for it. Confirm that the item isn’t missing any essential parts.
It’s not uncommon for prior owners of all sorts of used equipment to make structural modifications so that they work better in their specific spaces. However, this can cause problems if you purchase such altered items and remain unaware of the changes. Adjustments that might’ve worked well in a different context could potentially frustrate your end use.
At Surplus Record, we urge both sellers and buyers of used equipment to take and examine photos covering as much of the equipment as is feasible. The reason why is that we don’t want hidden damage (such as rust on the interior of a spray booth) to go unnoticed.
Even if you’ve purchased the best powder coating machines, it won’t much matter if they don’t fit in your space. In addition to measuring out your available space, make sure that any powder coating equipment you purchase fit into your workflow.
Air Velocities Strength
Faster and stronger isn’t always better when it comes to powder coating. Velocities that are too low run the risk of inadequate coating, while stronger velocities could cause powder to drift outside of a booth. The generally agreed upon velocity in powder coating is 100 to 120 feet per minute.
Real-Life Applications of Powder Coating Machines
Due to its strength, long life, and environmental friendliness, powder coating has numerous real-world applications, including:
- Household Appliances
- Vending Machines
- Electrical Fixtures
- Car Rims
- Farm Equipment
- Bicycle and Vehicle Frames
- Sports Equipment
- Propane Equipment
- Windows and Doors
- Military Equipment
- Electrical Transformers
- Building Facades
- Electrical Junction Boxes
- HVAC Systems
- Housings for Electronics
- Medical Equipment
Accessories for Powder Coating Machines
Because powder coating equipment is incredibly customizable, you can expect to find numerous accessories and spare parts available in both used and new markets. In this section, we will detail the various kinds of accessories you can expect to see by category.
Hoppers and kegs are storage containers for powder, and they tend to group according to size and material. Some are designed to allow smooth, consistent operations even with very small amounts of powder (e.g., vortex cups), while others boast easy cleanability (e.g., hoppers made out of stainless steel). Examples of hoppers, kegs, and related equipment include:
- Vortex Cups
- Mini Hoppers
- Steel Fluidization Hoppers
- Powder Kegs
- Cup-Feed Stations
- Fluidizing Hopper Replacement Gaskets
- Standard Hopper Replacement Gaskets
For smaller systems, powder-coating pumps come in two basic configurations. They can have straight pump bodies where the intake sits perpendicularly to outflow, or they can be arranged at an angle. Larger, factory-sized pumps interface with spray tunnels either horizontally or vertically. All of these configurations require different kinds of accessories.
While powder-coating guns come in different configurations and types, they generally all have similar accessories, some of which include the following:
- Mounting Rods and Brackets
- Power Supplies
Similarly, the accessories for powder-coating ovens are primarily replacement parts or supplemental items designed to make proper operation easier, such as:
- Electric Oven elements (110v or 220v)
- Horizontal Hanging Racks
- Vertical Hanging Racks
- Infrared Curing Lamps
- Non-Contact Thermometers
- Lamp Stands
Booths can fulfill many tasks in the powder-coating process, everything from simply containing spray and maintaining safe airflow to recycling overspray for future use. Booth accessories include:
- Box Filters
- Spray Filter Pulsation (4 and 6 Filter Valves)
- Air Manifolds
- Horizontal Hanging Racks
- Vertical Hanging Racks
If you’re considering purchasing powder coating equipment or any spare parts or accessories, see what Surplus Record has available. Search for “paint and powder systems” at the top of the Surplus Record website to see the available selection.
Popular manufacturers of powder coating products and equipment include Nordson, Wagner, Illinois Tool Works, and Iontech.